Ultrahigh-pressure fan jet nozzle

ABSTRACT

A nozzle for producing an ultrahigh-pressure fluid fan jet is shown and described. In a preferred embodiment, the nozzle has an inner surface defined by a conical bore extending from a first end to a second end, thereby creating an entrance orifice and an exit orifice in the first and second ends, respectively. A wedge-shaped notch extends inward from the second end towards the first end to a sufficient depth such that the shape of the exit orifice is defined by the intersection of the conical bore and the wedge-shaped notch. As pressurized fluid passes through the nozzle and out the exit orifice, the shape of the exit orifice causes the pressurized fluid to exit in the form of a fan jet having a substantially oval cross-section. This fan jet may be swept across a surface to be cleaned thereby selectively removing a layer of material from an underlying surface evenly and completely, without damaging the underlying surface. The fan jet may also be used to cut a fibrous or hard material.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.08/388,369, filed Feb. 14, 1995, now abandoned, which is a divisional ofU.S. patent application Ser. No. 08/198,645, filed Feb. 18, 1994, nowissued as U.S. Pat. No. 5,417,607.

TECHNICAL FIELD

This invention relates to nozzles, and more particularly, to nozzles foruse in connection with ultrahigh-pressure fluid jets.

BACKGROUND OF THE INVENTION

Numerous tasks, for example cutting, cleaning, milling, and kerfing, maybe accomplished through the use of a stream of pressurized fluid,typically water, generated by high-pressure, positive displacement pumpsor other suitable means. Such pumps pressurize a fluid by having areciprocating plunger that draws the fluid from an inlet area into apressurization chamber during an intake stroke, and acts against thefluid during a pumping stroke, thereby forcing pressurized fluid to passfrom the pressurization chamber into an outlet chamber, from which it iscollected into a manifold. The pressurized fluid is then directedthrough the nozzle of a tool thereby creating an ultrahigh-pressure jetthat may be used to perform a particular task, for example cutting asheet of metal or cleaning a surface, such as on aircraft parts. Suchjets may reach pressures up to and beyond 55,000 psi.

In the past, such ultrahigh-pressure fluid tasks have been accomplishedusing nozzles that produce a column of pressurized fluid having acircular cross-section. Rotating such a round jet is equivalent tomoving a point. As a result, a round jet may be well-suited for directuse in certain tasks, for example, cutting out odd shapes such as adiaper. For other tasks, such as cleaning, round jets require relativelycomplex methods of use and may not provide optimum results.

For example, when cleaning a surface, it is desirable and oftennecessary to remove a layer of matter from an underlying surface withoutdamaging the underlying surface. It is also often necessary to have a100% clean surface. To clean a surface with a round jet, it is necessaryto move the round jet, or point, in a circular pattern in an attempt toclean the entire surface. However, such a method produces a pattern inwhich some areas on the surface being cleaned are hit multiple timeswhile other areas of various shapes are not hit at all by the jet. As aresult, the surface is not 100% clean, and the underlying surface willbe damaged and uneven.

A need therefore exists for an improved method of cleaning surfaces andaccomplishing other ultrahigh-pressure fluid tasks.

SUMMARY OF THE INVENTION

It is therefore an object of this invention to provide an improvedmethod of cleaning surfaces.

It is another object of this invention to provide a nozzle that willproduce an ultrahigh-pressure fluid jet that will uniformly remove alayer of matter from an underlying surface without damaging theunderlying surface.

It is another object of this invention to provide a nozzle that issimple to manufacture that will produce consistent results.

These and other objects of the invention, as will be apparent herein,are accomplished by providing an ultrahigh-pressure fan jet nozzle. In apreferred embodiment, the nozzle has an inner surface defined by aconical bore that extends from a first end of the nozzle to a second endof the nozzle. As a result, the first end is provided with an entranceorifice through which a volume of pressurized fluid may enter the nozzleand the second end is provided with an exit orifice through which thepressurized fluid may exit after passing through the body of the nozzle.The second end of the nozzle is further provided with a wedge-shapednotch that extends from its widest point at the second end in towardsthe first end of the nozzle, intersecting the exit orifice. As a result,the shape of the exit orifice is defined by the intersection of theconical bore and the wedge-shaped notch. The shape of the exit orificecauses the pressurized fluid leaving the nozzle to do so as a fan jet,having a substantially linear footprint, the width of which varies withchanges in the geometry of the nozzle. For purposes of discussion, thefootprint may be viewed as a thin rectangle, or as an oval having a veryhigh aspect ratio, such as 100 to 1, having a major axis and a minoraxis. This fan jet may be swept across a surface to be cleaned in thedirection of the minor axis of the footprint to selectively remove alayer of material. Alternatively, the fan jet may be swept across asurface to be cut in the direction of the major axis of the footprint,thereby producing a shearing, cutting force. Such a fan jet may beparticularly well suited to cutting fibrous materials, although it wouldalso provide an accurate, straight cut in a hard material.

The power distribution of the fan jet may be controlled by changing aninternal angle of the conical bore and an angle of the wedge-shapednotch. This is beneficial because different power distributions may bemore appropriate than others for a particular task. For example, in thecontext of cleaning as discussed above, it is believed to be desirableto have a fan jet with a uniform power distribution, which may beaccomplished by correctly adjusting the geometry of the nozzle.

In a preferred embodiment, an outer surface of the nozzle is alsoconical such that the second end has a substantially circular, planarsurface. In addition, the wedge-shaped notch is aligned with a diameterof the circular planar surface such that the resulting fan jet will bevertically aligned with a longitudinal axis of the nozzle. In analternative embodiment, the wedge-shaped notch may be offset such thatit is not aligned with a diameter of the surface of the second end,thereby producing a "side-firing" fan jet that exits the nozzle at anangle relative to the longitudinal axis of the nozzle. Such aside-firing jet may also be produced by grinding the wedge-shaped notchat an angle relative to the longitudinal axis of the nozzle, such thatthe axis of the nozzle is not in the plane of the notch.

In a yet another alternative embodiment, the wedge-shaped notch may beat an angle relative to the longitudinal axis of the nozzle such thatthe axis of the nozzle is in the plane of the notch. This produces an"angled" fan jet.

In a preferred embodiment illustrated herein, the nozzle is mounted in areceiving cone such that when a volume of pressurized fluid passesthrough the nozzle, the receiving cone acts against the nozzle causingthe inner walls of the nozzle near and at the exit orifice to be in acompressive state of stress. This condition increases the nozzle'sresistance to fatigue and wear.

In a preferred embodiment, the nozzle is manufactured by machining out aconical bore from a blank of annealed stainless steel. The internalsurface of the nozzle is finished by pressing a cone-shaped die into theconical bore, thereby eliminating machining marks and improving theinner surface quality. The part is then heat treated, before or afterwhich the outer surface of the nozzle may be finished. Once the part isheat treated, a wedge-shaped notch is machined out of the second end ofthe nozzle to a sufficient depth such that a shape of the exit orificeis defined by the intersection of the conical bore and the wedge-shapednotch.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example of a pattern made by a prior art circular jet whenrotated and travered across a surface.

FIG. 2. is a cross-sectional view of a nozzle illustrating a preferredembodiment of the present invention.

FIG. 3 is a cross-sectional view of the nozzle of FIG. 2 mounted in areceiving cone.

FIGS. 4a-c are diagrams illustrating the effect of changing an internalcone angle of the nozzle of FIG. 2 on the power distribution of aresulting fan jet.

FIGS. 5a-c are diagrams illustrating the effect of changing an externalwedge angle of the nozzle of FIG. 2 on the shape of the resulting fanjet.

FIGS. 6a-b are bottom plan views illustrating alternative embodiments ofthe nozzle of FIG. 2.

FIGS. 7a-c are diagrams illustrating front and side views of threealternative embodiments the nozzle of FIG. 2 and resulting fan jets.

FIG. 8 is a top plan view of a grinding fixture used to manufacture thenozzle of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

Various tasks such as cutting, cleaning, milling, and kerfing may beaccomplished through the use of an ultrahigh-pressure fluid jet. Suchjets may be generated by high-pressure, positive displacement pumps (notshown) and may reach pressures up to and beyond 55,000 psi. Thepressurized fluid generated by the pump is typically collected in amanifold from which the fluid is directed through the nozzle of a tool(not shown), thereby creating an ultra-high pressure jet that may beused to perform a particular task.

In the current state of the art, a column of pressurized fluid having acircular cross section is typically used. Although circular jets arebeneficial in certain applications, for example cutting complex shapes,a moving circular jet represents a moving point and therefore has severelimitations in other contexts such as cleaning. The current practice incleaning a surface with a circular jet is to rotate and translatecircular jets along a surface, resulting in the pattern 11 shown inFIG. 1. As illustrated in FIG. 1, there are various shaped areas such asdiamonds 13, crescents 15, and triangles 17, among others, that arenever hit by the rotating and translating jets (not shown). In addition,as illustrated in FIG. 1 at 19, there are several areas on the surfacethat are hit by the jets multiple times. As a result, the surface is notcleaned completely or evenly, resulting in a damaged surface.

FIGS. 2 and 3 illustrate a preferred embodiment of the presentinvention. A nozzle 12 has a first end 14, a second end 16, an outersurface 18 and an inner surface 20. The inner surface 20 is defined by aconical bore 22, that extends from the first end 14 to the second end16, thereby creating an entrance orifice 24 and an exit orifice 26 inthe first end 14 and second end 16, respectively. A wedge-shaped notch28 extends from the second end 16 in towards the first end 14 to a depth44 such that the notch 28 and conical bore 22 intersect. The shape ofthe exit orifice 26 is therefore defined by this intersection of theconical bore 22 and the wedge-shaped notch 28. As a volume ofpressurized fluid passes through the nozzle 12 and out the exit orifice26, the shape of the exit orifice 26 causes the pressurized fluid toexit the nozzle as a fan jet, having a substantially linear footprint.

As illustrated in FIG. 3, the nozzle 12 in a preferred embodiment ismounted within a receiving cone 30, including a nozzle nut 31. Aspressurized fluid passes through the receiving cone 30 and the nozzle12, the receiving cone 30 acts against the nozzle 12 thereby placing theinner surface 20 of the nozzle 12 near and at the exit orifice 26 in acompressive state of stress. By being in compression rather thantension, the nozzle 12 is more resistant to fatigue and wear.

In a preferred embodiment, the outer surface 18 of the nozzle 12 isconical such that the second end 16 has a substantially circular planarsurface 45, as illustrated in FIG. 6a. The wedge-shaped notch 28 isaligned along a diameter of the circular surface 45, such that it passesthrough a center 47 of the second end 16. As a result, the fan jet ofpressurized fluid will exit the nozzle 12 in a direction substantiallyaligned with a longitudinal axis 50 of the nozzle 12. This fan jet maybe referred to as a "straight" fan 49, as illustrated in FIG. 7a. Astraight fan 49 may be useful in various contexts, for example, incleaning or coating removal, as will be discussed in greater detailbelow.

In an alternative embodiment, as illustrated in FIG. 6b, thewedge-shaped notch 28 is offset such that it is not aligned along adiameter of the circular surface 45 of the second end 16. As a result,the fan jet will exit the nozzle 12 at an angle relative to thelongitudinal axis 50 of the nozzle 12. Such a fan jet may be referred toas a "side-firing" fan 51, as illustrated in FIG. 7b. A side-firing fanjet 51 may also be produced by grinding the wedge-shaped notch 28 at anangle relative to the longitudinal axis 50 of nozzle 12, such that theaxis 50 of nozzle 12 is not in the plane of the notch 28. Side-firingfan jets 51 may be useful in various contexts, for example, when it isnecessary to clean or remove grout from sides of a narrow, deep area,such as a gap between two concrete blocks.

In yet another alternative embodiment, as illustrated in FIG. 7c, thewedge-shaped notch 28 may be at an angle relative to the longitudinalaxis 50 of the nozzle 12 such that the axis 50 of the nozzle 12 is inthe plane of the notch 28. This produces an "angled" fan jet 53, whichis believed to be useful in various contexts.

As discussed above, the pressurized fluid exiting the nozzle 12 is inthe form of a fan jet having a substantially linear footprint, the widthof which varies with changes in the geometry of the nozzle. For purposesof discussion, the footprint may be viewed as a thin rectangle, or as anoval having a very high aspect ratio, such as 100 to 1, having a majoraxis and a minor axis. The geometry of the fan jet may be controlled byadjusting the geometry of the nozzle, different geometries being moredesirable depending on the task at hand. For example, in cleaning it isoften desirable to selectively remove a layer of matter from anunderlying surface, without damaging the underlying surface. It is alsodesirable and often necessary to have a 100% clean surface. By sweepingthe fan jet produced by the preferred embodiment of the nozzle 12illustrated herein across a surface to be cleaned in the direction ofthe minor axis of the fan jet's footprint, it is possible to remove alayer of material evenly and completely, thereby avoiding the problemsassociated with the rotation and translation of a circular jet. It willbe appreciated by one of ordinary skill in the art, that a number ofnozzles 12 may be aligned and translated across a surface in unison toclean a larger area more quickly and efficiently. Alternatively, the fanjet may be swept across a surface to be cut in the direction of themajor axis of the footprint, thereby providing a shearing, cuttingforce. Such a fan jet may be particularly well suited to cutting fibrousmaterials, although it would also provide an accurate, straight cut in ahard material.

As illustrated in FIGS. 4a-c, the geometry of the nozzle 12 may bealtered to control the resulting geometry and power distribution of thefan jet. For example, as discussed in the cleaning illustration above,it is desirable to have a uniform power distribution along a width ofthe fan jet thereby resulting in an even distribution of power acrossthe surface being cleaned. In a preferred embodiment, as illustrated inFIG. 4a, an internal angle 34a of the conical bore 22 is 90° to achievea uniform power distribution 36a of the fan jet, such that the power atthe center 40a at the ends 42a of the fan jet is the same. In analternative embodiment, as illustrated in FIG. 4b, the internal angle34b of the conical bore 22 is less than 90°, for example, 60°, therebyresulting in a power distribution 36b that is concentrated at a center40b of the fan jet and tapers at the ends 42b of the fan jet. In anotheralternative embodiment, as illustrated in FIG. 4c, an internal angle 34cof the conical bore 22 is greater than 90°, for example, 105°, resultingin a power distribution 36c that is concentrated on the ends 42c of thefan jet and minimal at the center 40c of the fan jet. Each of theseconfigurations has its own uses. For example, the even powerdistribution illustrated in FIG. 4a is preferred for many cleaning tasksbecause it acts uniformly along its width against the surface to becleaned.

As illustrated in FIGS. 5a-c, changes to an external angle 33 of thewedge-shaped notch 28 may be made to control the shape and thickness ofthe fan jet. As illustrated in FIG. 5a, a small wedge angle 33a producesa wide-angled fan 35, while a large wedge angle 33c, as shown in FIG.5c, produces a narrow-angled fan 37. Although not shown, the thicknessof the fan jet also increases with an increase in the wedge angle.Again, different configurations have different applications, forexample, a narrow-angled fan such as that produced by the wide -angledwedge angle in FIG. 5c will be more focused in delivering power to atarget, which may be necessary if the distance between the nozzle 12 andthe surface being cleaned is great.

The nozzle 12 is manufactured by machining a blank 64 from anyhigh-strength, metallic alloy, for example, annealed steel. In apreferred embodiment, the nozzle 12 is made from Carpenter Custom 455stainless steel. The conical bore 22 is machined out of the blank, afterwhich the inner surface 20 is finished by pressing a cone-shaped die(not shown) into the conical bore 22, thereby eliminating machiningmarks and improving the quality of the inner surface 20. The nozzle 12is then heat treated at a given temperature for a given amount of time,to increase the strength of the material. The correct temperature andtime are dependent on the material used, and will be known by one ofordinary skill in the art. For example, in a preferred embodiment, wherethe nozzle is made from Carpenter Custom 455, the nozzle is treated at900° F. for four hours, and then air cooled. The outer surface 18 of thenozzle 12 may be finished before or after the nozzle is heat treated. Ina preferred embodiment, the outer surface 18 is conical, such that thesecond end 16 has a substantially circular, planar surface 45.

The wedge-shaped notch 28 is then machined into the second end 16 of theblank 64, or nozzle 12, to a sufficient depth such that the notch 28intersects the exit orifice 26 created by the conical bore 22. Asillustrated in FIG. 8, the grinding fixture 59 includes two diamonddressers 60 which may be positioned to create a desired angle such thatwhen the dressers 60 act against a grinding wheel 62, they will producethe same angle on the edge of the grinding wheel 62. Several of theblanks 64 are mounted on a turret 66, which may move both laterally andlongitudinally to align the blank 64 with the grinding wheel 62. As thegrinding wheel 62 acts against the blank 64 to create the wedge-shapednotch 28, the angle of which corresponds to the desired angle of thedressers and grinding wheel, lubricants are used to cool the machineryand prevent damage, the method and necessity of which will be understoodby one of ordinary skill in the art.

A first blank 64 is used to calibrate the system. An operator of thegrinding fixture 59 grinds a wedge-shaped notch 28 into the blank 64,and then rotates the turret 66 90° to inspect the alignment of thewedge-shaped notch 28 with the conical bore 22. This inspection is donethrough a microscope (not shown). If the wedge-shaped notch 28 is notproperly aligned, adjustments are made by moving the turret 66. Once thedesired alignment is achieved, multiple nozzles 12 may then be completedvery quickly by mounting multiple blanks 64 on the turret 66 andgrinding the wedge-shaped notch 28 via the grinding wheel 62. Inaddition, different depths of the wedge-shaped notch 28 will be desired,depending on the intended task and the size of the nozzle, as measuredby a diameter of the nozzle 12. The desired depth is calibrated andchecked by measuring the length of a minor axis of the exit orifice 26which will have an oval shape due to the intersection of thewedge-shaped notch 28 and the conical bore 22.

A nozzle for generating an ultrahigh-pressure fluid fan jet has beenshown and described. From the foregoing, it will be appreciated that,although embodiments of the invention have been described herein forpurposes of illustration, various modifications may be made withoutdeviating from the spirit and scope of the invention. Thus, the presentinvention is not limited to the embodiments described herein, but ratheris defined by the claims which follow.

We claim:
 1. An ultrahigh-pressure fan jet nozzle for use in a systemhaving a pump to pressurize a volume of fluid to at least 30,000 psiupstream of an entrance orifice of the nozzle to perform a task via atool, the nozzle comprising:a first end, a second end, an outer surfaceand an inner surface, the inner surface being defined by a boreextending through the nozzle from the first end to the second end suchthat the first end is provided with the entrance orifice and the secondend is provided with an exit orifice and the pressurized fluid can enterthe nozzle through the entrance orifice, pass through the nozzle and outthe exit orifice to perform the task, the bore having a cylindricalsection extending from the first end towards the second end andterminating in a conical section, an internal angle of the conicalsection of the bore near the exit orifice being 90° such that a powerdistribution of the fan jet is uniform along a width of the fan jet, thecylindrical section and the conical section having equal diameters attheir point of intersection and being symmetrically aligned along alongitudinal axis of the body; and wherein a wedge-shaped notch extendsfrom the second end in towards the first end only until the wedge-shapednotch intersects an end region of the conical section of the bore, suchthat a shape of the exit orifice is defined by the intersection of theend region of the conical section of the bore and the wedge-shaped notchsuch that the exit orifice causes the pressurized fluid to exit thenozzle as an ultrahigh-pressure fan jet.
 2. An ultrahigh-pressure fanjet nozzle for use in a system having a pump to pressurize a volume offluid to at least 30,000 psi upstream of an entrance orifice of thenozzle to perform a task via a tool, the nozzle comprising:a first end,a second end, an outer surface and an inner surface, the inner surfacebeing defined by a bore extending through the nozzle from the first endto the second end such that the first end is provided with the entranceorifice and the second end is provided with an exit orifice and thepressurized fluid can enter the nozzle through the entrance orifice,pass through the nozzle and out the exit orifice to perform the task,the bore having a cylindrical section extending from the first endtowards the second end and terminating in a conical section, an internalangle of the conical section of the bore near the exit orifice beingless than 90° such that a power distribution of the fan jet isconcentrated near a center of the fan jet and tapers off toward an endof the fan jet, the cylindrical section and the conical section havingequal diameters at their point of intersection and being symmetricallyaligned along a longitudinal axis of the body; and wherein awedge-shaped notch extends from the second end in towards the first endonly until the wedge-shaped notch intersects an end region of theconical section of the bore, such that a shape of the exit orifice isdefined by the intersection of the end region of the conical section ofthe bore and the wedge-shaped notch such that the exit orifice causesthe pressurized fluid to exit the nozzle as an ultrahigh-pressure fanjet.
 3. A method for cutting a fibrous or hard materialcomprising:forcing a volume of pressurized fluid at a pressure of atleast 30,000 psi through a nozzle having a first end, a second end, anouter surface and an inner surface, the inner surface being defined by abore extending through the nozzle from the first end to the second endsuch that the first end is provided with an entrance orifice and thesecond end is provided with an exit orifice and the pressurized fluidmay pass through the entrance orifice, through the nozzle and out theexit orifice to perform the task, the bore having a cylindrical sectionextending from the first end towards the second end and terminating in aconical section, the cylindrical section and the conical section beingsymmetrically aligned along a longitudinal axis of the body, and whereina wedge-shaped notch extends from the second end in towards the firstend only until the wedge-shaped notch intersects an end region of theconical section of the bore, such that a shape of the exit orifice isdefined by the intersection of the end region of the conical section ofthe bore and the wedge-shaped notch and wherein the exit orifice causesthe pressurized fluid to exit the nozzle as a fan jet having asubstantially linear footprint; and sweeping the fan jet across thematerial to be cut in a direction of a major axis of the footprint. 4.An ultrahigh-pressure fan jet nozzle for use in a system having a sourceof ultrahigh-pressure fluid provided upstream of an entrance orifice ofthe nozzle, the nozzle comprising:a body having a first end, a secondend, an outer surface and an inner surface, the inner surface beingdefined by a bore extending through the body from the first end to thesecond end such that the first end is provided with the entrance orificeand the second end is provided with an exit orifice and a volume ofultrahigh-pressure fluid can enter the nozzle through the entranceorifice, and pass through the nozzle and out the exit orifice, the borehaving a cylindrical section extending from the first end towards thesecond end and terminating in a conical section, an internal angle ofthe conical section of the bore near the exit orifice being 90° suchthat a power distribution of the fan jet is uniform along a width of thefan jet, the cylindrical section and the conical section having equaldiameters at their point of intersection and being symmetrically alignedalong a longitudinal axis of the body; and wherein a wedge-shaped notchextends from the second end in towards the first end only until thewedge-shaped notch intersects an end region of the conical section ofthe bore, such that a shape of the exit orifice is defined by theintersection of the end region of the conical section of the bore andthe wedge-shaped notch and is symmetric about both a major and a minoraxis.
 5. An ultrahigh-pressure fan jet nozzle for use in a system havinga source of ultrahigh-pressure fluid provided upstream of an entranceorifice of the nozzle, the nozzle comprising:a body having a first end,a second end, an outer surface and an inner surface, the inner surfacebeing defined by a bore extending through the body from the first end tothe second end such that the first end is provided with the entranceorifice and the second end is provided with an exit orifice and a volumeof ultrahigh-pressure fluid can enter the nozzle through the entranceorifice, and pass through the nozzle and out the exit orifice, the borehaving a cylindrical section extending from the first end towards thesecond end and terminating in a conical section, an internal angle ofthe conical section of the bore near the exit orifice being less than90° such that a power distribution of the fan jet is concentrated near acenter of the fan jet and tapers off toward an end of the fan jet, thecylindrical section and the conical section having equal diameters attheir point of intersection and being symmetrically aligned along alongitudinal axis of the body; and wherein a wedge-shaped notch extendsfrom the second end in towards the first end only until the wedge-shapednotch intersects an end region of the conical section of the bore, suchthat a shape of the exit orifice is defined by the intersection of theend region of the conical section of the bore and the wedge-shaped notchand is symmetric about both a major and a minor axis.
 6. Anultrahigh-pressure fan jet nozzle for use in a system having a source ofultrahigh-pressure fluid provided upstream of an entrance orifice of thenozzle, the nozzle comprising:a body having a first end, a second end,an outer surface and an inner surface, the inner surface being definedby a bore extending through the body from the first end to the secondend such that the first end is provided with the entrance orifice andthe second end is provided with an exit orifice and a volume ofultrahigh-pressure fluid can enter the nozzle through the entranceorifice, and pass through the nozzle and out the exit orifice, the borehaving a cylindrical section extending from the first end towards thesecond end and terminating in a conical section, an internal angle ofthe conical section of the bore near the exit orifice being greater than90° such that a power distribution of the fan jet is concentrated at anend of the fan jet and minimal near a center of the fan jet, thecylindrical section and the conical section having equal diameters attheir point of intersection and being symmetrically aligned along alongitudinal axis of the body; and wherein a wedge-shaped notch extendsfrom the second end in towards the first end only until the wedge-shapednotch intersects an end region of the conical section of the bore, suchthat a shape of the exit orifice is defined by the intersection of theend region of the conical section of the bore and the wedge-shaped notchand is symmetric about both a major and a minor axis.